Magnus Carlsen recovered from a terrible start of two defeats in three games, escaped miraculously from a lost endgame, triumphed at this week's London Classic, won the €50,000 first prize and regained the world No1 ranking. Yet arguably the 20-year-old Norwegian's play continued the form crisis which surfaced in October at the world team Olympiad.

The problem is that Carlsen is a different player according to whether he has White or Black. With the white pieces he is sovereign and supreme, exploiting strategic advantages with the subtlety of Anatoly Karpov in his pomp, or patiently grinding and probing in level positions until his opponent cracks in time pressure.

But as Black Carlsen simply tries too hard. Sometimes this impatience becomes manifest when he plays too actively in a level position, as against the world champion, Vishy Anand, in London. And sometimes it shows in his choice of offbeat openings, as in his notorious 1 e4 g6 2 d4 Nf6?! 3 e5 Nh5?! against Michael Adams in the Olympiad. In the game below he also produced a strange knight regroup Nd7-e5-d7-c5 which conceded the initiative to Luke McShane. The Englishman exploited his edge in style.McShane's own knight forays 18 Nc6! and 22 Na6! looked eccentric but were sharply and accurately calculated.

Luke McShane had the result of his life, justifying his decision to turn his back on a City career and become a full-time chess pro. He would have tied first with Carlsen and Anand on 4.5/7 under traditional scoring (1 point win, 0.5 draw) but the 3/1 system used in London favoured Carlsen. At age 26 and advancing fast up the world rankings, McShane has a chance to reach the elite.

Overall the Classic proved a fine shop window for top chess. Near sell-out crowds came every day to Olympia to watch the grandmasters play the legendary Viktor Korchnoi in simultaneous matches, listen to commentators including Garry Kasparov, compete in side events or simply relax with social games.